A vehicle is equipped with a differential device as a torque transmission device for smoothing a running state during turning etc. The differential device is disposed and interposed between left and right wheels, between front and rear wheels, etc., and the differential device generally includes a pair of side gears (bevel gears) arranged facing each other on the same axis and respectively coupled as a torque output member to a wheel on one side and a wheel on the other side of the vehicle, a supporting member disposed on the outer circumferential side of the pair of the side gears and rotating around the axis of the pair of the side gears as a torque input member, and a pinion gear (bevel gear) rotatably supported by the supporting member and engaged with the pair of the side gears in a straddling manner.
This enables absorption (adjustment) of a difference in the rotation number between inside and outside wheels and a difference in the rotation number between front and rear wheel during turning while the vehicle is running, and the turning can be made easier.
If a wheel on one side slips in mud, on a frozen road surface, etc., or a wheel on the inside of a turn lifts up (lift-in occurs) due to a centrifugal force during turning in an accelerated state in a vehicle equipped with the differential device, torque is no longer transmitted to a wheel on the other side on the ground. Therefore, a torque transmission device mounted on a vehicle has a differential device further including a differential limiting mechanism (diff-lock mechanism) as described in Patent Document 1 and, when a wheel on one side slips as described above, the differential limiting mechanism couples one of the side gears (specifically, axles) and the supporting member in the differential device by using a clutch mechanism. As a result, in such a case that a wheel on one side slips, the both side gears making a pair integrally rotate in accordance with rotation of the supporting member, so that a drive force can reliably be transmitted to a road surface through a wheel on the other side.